Problem: Solve for $a$ : $-6 = a - 10$
Answer: Add $10$ to both sides: $ \begin{eqnarray} \\ \hphantom{-6 {+ 10}} &\hphantom{=}& \hphantom{a} \\ -6 &=& a - 10 \\ \\ {+10} && {+10} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ -6 {+ 10} &=& a \\ \end{eqnarray} $ Simplify. $ a = 4$